Human and animal fossils are a window into the past that give us a connection between the present and the past. Scientists dug up a specimen that is so old and unique that it nudges back the origins of lizards, snakes, and the tuatara, and animals all part of a group called Lepidosauria.Fossils often tell stories through fragments, like bits of bone, teeth, or skull parts, but this one is special. Despite its size, it gives a clear window into life nearly 242 million years ago, during the Middle Triassic, long before dinosaurs ruled. It is a new perspective into how early reptiles looked and functioned, especially in how their skulls were built and how they fed.
Tuatara
This discovery matters because lepidosaurs today are everywhere, including the lizards, snakes, and the tuatara alone make up thousands of species.
What did the scientists find
Researchers at the University of Bristol have described a new species called Agriodontosaurus helsbypetrae, discovered in 2015 on a beach in Devon. According to their study published in Nature and summarized in a Bristol University press release, this reptile is now the oldest known lepidosaur and it lived in the Middle Triassic, about 242 million years ago.
What makes this discovery special?
Modern lepidosaurs, lizards, snakes, and the tuatara often share features like teeth on the roof of the mouth, a hinged skull, and an open lower temporal bar, which is a gap in the skull that helps with flexibility. The Devon fossil has none of those first two, but it does have the open lower temporal bar.
Tuatara
Dan Marke, lead author of the study, say, “The new fossil shows almost none of what we expected … It has no teeth on the palate, and no sign of any hinging. It does, though, have an open temporal bar, so one out of three. Not only this but it possesses some spectacularly large teeth compared to its closest relatives.”
It has triangular teeth
Even more interesting are the fossils’ teeth. A. helsbypetrae had large, triangular teeth, especially compared to its nearest relatives, likely used to pierce and shear the tough exoskeletons of insects. According to Professor Michael Benton, co‑supervisor of the research, “The new beast has relatively large triangular‑shaped teeth and probably used these to pierce and shear the hard cuticles of its insect prey, pretty much as the tuatara does today.”The skull is tiny, about 1.5 centimeters long, so studying it was tough. Using advanced tools like synchrotron X‑ray imaging, the scientists could see fine anatomical details without damaging the fossil.
Tuatara
What this tells us about reptile evolution
This specimen shows that early lepidosaurs were already playing with different skull shapes and feeding strategies rather than following a fixed blueprint. The presence of just one of the three expected skull features implies that traits like skull hinge and palate teeth evolved later or in different combinations.The tuatara gets described often as a “living fossil,” but this discovery adds to the detail. A. helsbypetrae demonstrates that the lineage the tuatara belongs to was once more diverse. The tuatara survived while many close relatives did not, carrying forward both ancestral and derived traits.